Effects of wind barriers on vortex-induced vibrations and vehicle aerodynamics of a steel Box–Truss girder

The steel box–truss composite girder is a newly developed structural form characterized by high stiffness and small mid-span deflection, and it has been increasingly applied in long-span high-speed railway bridges. However, due to complex aerodynamic interactions between the truss members and the box girder, its aerodynamic performance remains difficult to evaluate. Wind barriers, commonly installed to improve train operational stability, further complicate the aerodynamic coupling within the train–bridge system. This study, based on a long-span steel box–truss cable-stayed bridge, conducted 1:47 scale wind tunnel tests to analyze the effects of wind barrier parameters (height and porosity) on train aerodynamic coefficients and the vortex-induced vibration (VIV) performance of the bridge girder. Results show that the girder exhibits good resistance to VIV without wind barriers, but noticeable VIV responses may occur after their installation. Wind barriers also significantly affect the aerodynamic forces acting on the train. At a fixed porosity, increasing the barrier height leads to a reduction in the overturning moment coefficient, while increasing the porosity causes a slight increase in the overturning moment. Adding vertical stabilizing plates to the girder's inclined webs or bottom plate effectively suppresses VIV. Increased porosity further reduces vibration amplitude. Computational fluid dynamics (CFD) simulations reveal that these measures help disrupt periodic vortex shedding at the girder's trailing edge, providing an effective VIV mitigation strategy.